Microstructure through an Ice Sheet

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Abstract:

Ice cores through an ice sheet can be regarded as a sample of a unique natural deformation experiment lasting up to a million years. Compared to other geological materials forming the earth‘s crust, the microstructure is directly accessible over the full depth. Controlled sublimation etching of polished ice sections reveals pores, air bubbles, grain boundaries and sub-grain boundaries at the surface. The microstructural features emanating at the surface are scanned. A dedicated method of digital image processing has been developed to extract and characterize the grain boundary networks. First preliminary results obtained from an ice core drilled through the Greenland ice sheet are presented. We discuss the role of small grains in grain size analysis and derive from the shape of grain boundaries the acting driving forces for grain boundary migration.

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481-484

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March 2013

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[1] L. Arnaud, M. Gay, J.-M. Barnola, P. Duval, Imaging of firn and bubbly ice in coaxial reflected light: a new technique for the characterization of these porous media, J. Glaciol. 44 (1998), 326-332

DOI: 10.1017/s0022143000002653

Google Scholar

[2] S. Kipfstuhl, I. Hamann, A. Lambrecht, J. Freitag, S. Faria, D. Grigoriev, N. Azuma, Microstructure mapping: a new method for imaging deformation-induced microstructural features of ice on the grain scale, J. Glaciol. 52 (2006), 398-406

DOI: 10.3189/172756506781828647

Google Scholar

[3] I. Weikusat, A. Miyamoto, S.H. Faria, S. Kipfstuhl, N. Azuma, T. Hondoh, Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction, J. Glaciol. 57 (2011), 85-95

DOI: 10.3189/002214311795306628

Google Scholar

[4] T. Binder, C.S. Garbe, D. Wagenbach, J. Freitag, S. Kipfstuhl, Extraction and parameterization of grain boundary networks, using a dedicated method of automatic image analysis, J. Microsc. in review

DOI: 10.1111/jmi.12029

Google Scholar

[5] M. Herwegh, A new technique to automatically quantify microstructures of fine grains carbonate mylonites: two-step etching combined with SEM imaging and image analysis, J. Struct. Geol. 22 (2000), 391-400

DOI: 10.1016/s0191-8141(99)00165-0

Google Scholar

[6] A.J. Gow, On the rates of growth of grains and crystals in South Polar firn, J. Glaciol. 8 (1989), 241-252

DOI: 10.1017/s0022143000031233

Google Scholar

[7] I. Weikusat, S. Kipfstuhl, S.H. Faria, N. Azuma, A. Miyamoto, Subgrain boundaries and related microstructural features in EDML (Antarctica) deep ice core, J. Glaciol. 55 (2009), 461-472

DOI: 10.3189/002214309788816614

Google Scholar

[8] I. Hamann, C. Weikusat, N. Azuma, S. Kipfstuhl, Evolution of ice crystal microstructure during creep experiments, J. Glaciol. 53 (2007), 479-489

DOI: 10.3189/002214307783258341

Google Scholar